A Comment on “Modeling to Support Reliability Enhancement During Product Development With Applications in the U.K. Aerospace Industry”

The recent paper by L. Walls, J. Quigley, and J. Marshall, ldquoModeling to support reliability enhancement during product development with applications in the U.K. Aerospace industry,rdquo IEEE Trans. Eng. Manage., vol 53, no. 2, pp. 263-274, May 2006, claimed that there ldquowas no closed formrdquo for the meantime between failure defined to be the minimum order statistic of independent, nonidentically distributed beta random variables. It appears that this statement is not true. Here, we derive explicit closed-form expressions for moments of order statistics for a sample of independent and nonidentically distributed beta random variables. The expressions involve a known special function.